JP2012116920A - Method for producing polyoxymethylene resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyoxymethylene resin less prone to increase the amount of carbon dioxide in the atmosphere even when incinerated.SOLUTION: This method comprises a first step for producing formaldehyde from methanol, and a second step for producing a polyoxymethylene resin from the formaldehyde obtained in the first step, and uses, as the methanol used in the first step, methanol that may be methanol produced from a plant as a raw material. Preferably, methanol produced from glycerin obtained during the production of biodiesel is used as the methanol produced from a plant as a raw material.

Description

  The present invention relates to a method for producing polyoxymethylene.

  A group of resins called engineering plastics are used in various fields because they have excellent physical properties such as strength. For example, it is used as a resin part material when changing from a metal part to a resin part for weight reduction or the like.

  Among engineering plastics, polyoxymethylene resins have a high degree of crystallinity and are particularly excellent in terms of rigidity, strength, chemical resistance, solvent resistance, and the like. Because of such properties, polyoxymethylene resins are widely used mainly in the field of mechanical parts for automobiles and electrical equipment as injection molding materials (see, for example, Patent Document 1).

JP 2008-126523 A

  A general polyoxymethylene resin as described in Patent Document 1 is produced using methanol produced from fossil resources such as natural gas and coal (hereinafter, fossil resources such as natural gas) as a raw material. Since fossil resources such as natural gas are mined from the ground, incineration of polyoxymethylene resin produced by a general method increases the amount of carbon dioxide in the atmosphere. That is, incineration of a polyoxymethylene resin produced by a conventional method means that carbon is taken out from the ground and carbon dioxide is discharged into the atmosphere.

  As environmental and resource problems in recent years, countermeasures for increasing greenhouse gases such as carbon dioxide and countermeasures for future depletion of fossil resources are socially demanded. As described above, when the polyoxymethylene resin is incinerated, the amount of carbon dioxide in the atmosphere increases. For this reason, a method for solving the above-mentioned problem of increasing the amount of carbon dioxide in the atmosphere and making the polyoxymethylene resin a material with a low environmental load is required.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a polyoxymethylene resin that hardly increases the amount of carbon dioxide in the atmosphere even when incinerated. .

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, the inventors have focused on the fact that if a polyoxymethylene resin is produced from methanol produced from a plant as a raw material, the amount of carbon dioxide in the atmosphere will not be increased, and the present invention has been completed. More specifically, the present invention provides the following.

  (1) A first step of producing formaldehyde from methanol and a second step of producing a polyoxymethylene resin from the formaldehyde obtained in the first step, wherein the methanol is made from plant-based methanol. A method for producing a polyoxymethylene resin.

  (2) The said methanol is a manufacturing method of the polyoxymethylene resin as described in (1) manufactured using the glycerol obtained at the time of biodiesel manufacture as a raw material.

  (3) The method for producing a polyoxymethylene resin according to (1) or (2), wherein the second step is a step of producing trioxane from formaldehyde and producing a polyoxymethylene resin from the trioxane.

  (4) The method for producing a polyoxymethylene resin according to (3), wherein a polyoxymethylene resin is produced by copolymerizing the trioxane and a cyclic ether.

  (5) The method for producing the polyoxymethylene resin according to (4), wherein the cyclic ether is a cyclic ether made from a plant.

  In the present invention, the methanol used for producing the polyoxymethylene resin contains plant-derived methanol. Plants absorb carbon dioxide in the atmosphere in the process of growth for photosynthesis. As a result, even if polyoxymethylene resin produced using plant-derived methanol is incinerated to emit carbon dioxide, at least a part of the emitted carbon dioxide is absorbed by the plant in the atmosphere. It can be seen that it has just returned. That is, the increase amount of the carbon dioxide in air | atmosphere at the time of incinerating disposal of a polyoxymethylene resin can be suppressed rather than before.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment.

<Method for producing polyoxymethylene resin>
The manufacturing method of the polyoxymethylene of this invention is equipped with the 1st process of manufacturing formaldehyde from methanol, and the 2nd process of manufacturing a polyoxymethylene resin from the formaldehyde obtained at the said 1st process. Hereinafter, each step will be described.

[First step]
The first step is a step of producing formaldehyde from methanol. In the present invention, since methanol as a raw material includes those made from plants, even if the polyoxymethylene resin produced by the method of the present invention is disposed of by incineration, the increase in the amount of carbon dioxide in the atmosphere is higher than before. Can be suppressed.

  Although the manufacturing method of methanol manufactured using the plant used for this invention as a raw material is not specifically limited, For example, it can manufacture with the following method.

Methanol produced from plants used in the present invention is made from biomass such as solid components such as vegetation and paper waste and liquid components extracted from naturally derived organic components such as sugars and fats. By gasifying a synthesis gas mainly composed of hydrogen (H ₂ ), carbon monoxide (CO), and carbon dioxide (CO ₂ ) by a conventionally known general method, this gas is synthesized in the presence of a catalyst. Can be manufactured.

  A particularly advantageous method is a method of converting glycerin obtained from plant-derived material into methanol. In the present invention, it is particularly preferable to use glycerin produced as a by-product during the production of biodiesel. By using glycerin produced during the production of biodiesel, it is possible to use glycerin, which has been made unnecessary in the past, as a raw material. As a result, there is no need to provide a glycerin production process, which is industrially advantageous.

  Glycerin produced during the production of biodiesel is produced by subjecting plant-derived oils and fats, for example, primary alcohols, to transesterification in an alkaline environment. Glycerin from which biodiesel has been removed by purification from a mixture of biodiesel and glycerin after the transesterification reaction can be preferably used as a raw material for methanol production as described above.

  Examples of plant-derived oils and fats used in the production of methanol include palm oil, palm kernel oil, linseed oil, sunflower oil, tung oil, safflower oil, cottonseed oil, corn oil, sugarcane oil, soybean oil, rapeseed oil, canola oil, Sesame oil, rice oil, olive oil, peanut oil, castor oil, cocoa butter, coconut oil, safflower oil, curcas oil, mifukuragi oil, snubber oil and the like can be mentioned.

The method for producing methanol from the glycerin obtained as described above is not particularly limited. For example, first, glycerin is purified, then, if necessary, hydrocarbons and water vapor are added and reacted at a predetermined temperature under a nickel-based catalyst to produce hydrogen (H ₂ ), carbon monoxide (CO) and carbon dioxide. A synthesis gas mainly composed of (CO ₂ ) is generated. Next, the synthesis gas is reacted at a predetermined pressure and temperature on a copper / zinc-based methanol synthesis catalyst to synthesize crude methanol. Finally, methanol is obtained through a general distillation process. In this case, the added hydrocarbon may be derived from plants or derived from fossil resources such as natural gas, and the purity of methanol derived from plants can be arbitrarily adjusted.

  In the first step, the methanol used as a raw material may further include methanol produced from fossil resources such as natural gas, in addition to the above-mentioned methanol derived from vegetable oil. When plant-derived methanol and methanol derived from fossil resources such as natural gas are mixed, the mixing ratio is not particularly limited. However, the larger the amount of plant-derived methanol used, the smaller the environmental load. That is, when the polyoxymethylene resin is incinerated, the effect of suppressing an increase in carbon dioxide in the atmosphere is great.

  In addition, the mixing ratio in the case of mixing plant-derived methanol and methanol derived from fossil resources such as natural gas can be appropriately adjusted in consideration of, for example, the production cost of the polyoxymethylene resin.

  The method for producing methanol derived from fossil resources such as natural gas is not particularly limited, and conventionally known methods can be employed. Examples of conventionally known methods include the following methods.

First, in a reformer, gaseous hydrocarbon and water vapor are reacted at a predetermined temperature under a nickel-based catalyst, and hydrogen (H ₂ ), carbon monoxide (CO), and carbon dioxide (CO ₂ ) as main components. To produce synthesis gas. Next, crude methanol is synthesized by reacting the synthesis gas with carbon monoxide and hydrogen or carbon dioxide and hydrogen at a predetermined pressure and temperature on a copper or zinc-based methanol synthesis catalyst. Finally, methanol is obtained through a general distillation process.

  The methanol used as a raw material in the first step is methanol produced from the above plant as a raw material, or a mixture of this methanol and methanol produced from fossil resources such as natural gas.

  A method for producing formaldehyde from methanol is not particularly limited, and examples thereof include a silver contact method and a Formox method. The silver contact method is a method in which methanol is dehydrogenated or oxydehydrogenated in the presence of a silver catalyst or a copper catalyst. The Formox method is a method in which methanol is oxidized in the presence of a molybdenum oxide catalyst containing iron.

[Second step]
The second step is a step of producing a polyoxymethylene resin from the formaldehyde obtained in the first step. The polyoxymethylene resin produced in the second step may be a homopolymer or a copolymer.

  In the case of a homopolymer, for example, formaldehyde and a known molecular weight regulator are used as raw materials, a known organic amine, an organic or inorganic tin compound, a basic polymerization catalyst such as a metal hydroxide, and a solvent such as hydrocarbon. A polyoxymethylene resin can be obtained by a known general polymerization method and terminal stabilization method.

As a method for producing the copolymer, there are a copolymerization method using a formaldehyde alone as a main monomer and a copolymerization method using a formaldehyde derivative as a main monomer. The formaldehyde derivative is represented by the general formula (CH ₂ O) n (where n is an integer of 3 or more), and a representative example is trioxane, which is a cyclic triplet of formaldehyde. Trioxane is generally obtained by heating an aqueous formaldehyde solution in the presence of an acidic catalyst. For example, the trioxane can be purified and used by distillation or the like after heating.

  In the copolymerization method, a comonomer is used as an auxiliary material in addition to the main monomer. Examples of the comonomer include known cyclic ethers (including cyclic formal). Specifically, ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane, 1,3-dioxolane, propylene glycol Examples include cyclic ethers such as formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, and 1,6-hexanediol formal. These may be used as a mixture.

  With respect to the comonomer, by using a part or all of plant-derived raw materials in the synthesis, it becomes a comonomer made of plant raw materials, and by using this, a polyoxymethylene resin with a smaller environmental load can be obtained. As a plant-derived comonomer, for example, 1,3-dioxolane can be synthesized from plant-derived ethylene glycol and the above-mentioned plant-derived formaldehyde by a known method.

  The amount of comonomer used is not particularly limited, and can be determined in consideration of physical properties such as rigidity and chemical resistance of the resulting polyoxymethylene resin.

It is also possible to add a molecular weight adjusting component during the polymerization. Examples of the molecular weight adjusting component include conventionally known low molecular weight acetal compounds, and specifically include alkoxy groups such as methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, and oxymethylene di-n-butyl ether. The compound which has is mentioned.
By using a plant-derived low molecular acetal, it is possible to obtain a polyoxymethylene resin having a smaller environmental load.

  Furthermore, it is also possible to polymerize by adding a conventionally known polyfunctional compound capable of forming a branched / crosslinked group such as a diglycidyl ether compound.

  Specific polymerization is performed in the presence of a catalyst. As the catalyst, a cationic polymerization catalyst is generally used. Specifically, lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, penta Antimony fluoride, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetate anhydrate, boron trifluoride triethylamine complex compound, etc. Boron trifluoride coordination compounds, perchloric acid, acetyl perchlorate, t-butyl perchlorate, hydroxyacetic acid, trichloroacetic acid, trifluoroacetic acid, p-toluenesulfonic acid and other inorganic and organic acids, triethyloxonium tetrafluoroborate , Triphenylmethyl hexafluoroantimonate, Lil diazonium hexafluorophosphate, complex salt compounds such as allyl diazonium tetrafluoroborate, diethyl zinc, triethyl aluminum, alkali metal salts such as diethyl aluminum chloride, heteropoly acid, one or more of such isopolyacid.

  These cationic polymerization catalysts can be used as they are, or can be diluted in advance with an organic solvent or the like, and the preparation method is not particularly limited.

  Further, the polymerization apparatus used for producing the polyoxymethylene resin is not particularly limited, and a conventionally known apparatus can be produced. Specifically, any of a batch type apparatus, a continuous type apparatus, and the like can be used. The polymerization temperature is preferably maintained at 40 ° C. or higher and 135 ° C. or lower.

  After polymerization in this way, a deactivation treatment is performed to stop the activity of the catalyst. The catalyst is deactivated by adding a basic compound or an aqueous solution thereof to a product reaction product discharged from the polymerization device after the polymerization reaction or a reaction product in the polymerization device. Basic compounds for neutralizing and deactivating the polymerization catalyst include ammonia, amines such as triethylamine, tributylamine, triethanolamine, and tributanolamine, or hydroxylation of alkali metals and alkaline earth metals. Salts and other known catalyst deactivators are used. Moreover, after the polymerization reaction, it is preferable to quickly deactivate these aqueous solutions by adding them to the product.

  After the polymerization method and the deactivation method are performed, washing, separation and recovery of unreacted monomers, drying, and the like are further performed by a conventionally known method as necessary. Furthermore, if necessary, stabilization treatment by a known method, such as decomposition removal of unstable end portions or sealing of unstable ends with a stable substance, is performed, and various necessary stabilizers are blended. Examples of the stabilizer used here include one or more of hindered phenol compounds, nitrogen-containing compounds, alkali or alkaline earth metal hydroxides, inorganic salts, carboxylates, and the like. it can. As described above, a copolymer polyoxymethylene resin can be obtained.

<Effect>
Finally, the effect of the present invention will be briefly described. First, the present invention produces a polyoxymethylene resin using plant-derived methanol as a raw material. Plants photosynthesize during growth. In other words, plants grow while absorbing carbon dioxide in the atmosphere. Even if polyoxymethylene resin produced from plants that absorb carbon dioxide in the atmosphere is incinerated and carbon dioxide is discharged, the carbon dioxide absorbed by the plants will return to the atmosphere. The increase in carbon dioxide will be suppressed. On the other hand, when polyoxymethylene resin produced from methanol produced using fossil resources such as conventional natural gas is incinerated, carbon that was present in the ground will be discharged into the atmosphere as carbon dioxide. And increase the amount of carbon dioxide in the atmosphere. When producing polyoxymethylene resin using a mixture of plant-derived methanol and methanol derived from fossil resources such as natural gas, the greater the amount of plant-derived methanol used, the greater the The effect of suppressing the increase in carbon is great.

  In the present invention, it is industrially advantageous to produce plant-derived methanol from glycerin obtained at the time of biodiesel production.

  When a copolymer polyoxymethylene resin is used, the copolymer component is made a plant-derived raw material, so that the resin is further reduced in environmental load.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
A reaction tube containing an iron-containing molybdenum oxide catalyst (obtained by a known method of precipitating, filtering, washing, drying, crushing, shaping and firing iron molybdate from a mixture of molybdate and an aqueous solution of iron salt) Filled. Next, methanol (manufactured by BioMCN, 70% plant-derived) produced from glycerin produced when obtaining biodiesel, oxygen, and nitrogen are mixed in a ratio of 6.6: 23.4: 70.0 (methanol: oxygen: nitrogen). The mixed gas contained in the above was flowed into the reaction tube, and methanol was oxidized to produce an aqueous formaldehyde solution. The oxidation reaction was performed at 320 ° C. The reaction gas was stopped with water in a stripping column packed with Raschig rings. By this operation, 90 mol% of methanol was converted to formaldehyde. The formaldehyde aqueous solution contained 25% by mass of formaldehyde.

  Next, 99 parts by mass of the aqueous formaldehyde solution obtained by concentrating the aqueous formaldehyde solution to 50% by mass and 1 part by mass of sulfuric acid as a catalyst were mixed and reacted at 110 ° C. for 1.5 hours. Trioxane was obtained from the gas phase part of this reaction. The conversion of formaldehyde to trioxane was 20%.

  A jacket which passes a heat (cold) medium on the outside, a barrel having a shape in which two circles partially overlap each other and a rotating shaft with a paddle is used as a polymerization machine, and a 80 A trioxane containing 3.3% by mass of 1,3-dioxolane was continuously supplied to one end of the polymerization machine while passing two warming shafts at 0 ° C. and rotating two rotating shafts with paddles at 150 rpm, respectively. Furthermore, 0.1% by mass of methylal as a molecular weight regulator and a dibutyl ether solution of boron trifluoride dibutyl etherate as a catalyst are continuously added and supplied to trioxane so that the amount is 0.003% by mass in terms of boron trifluoride. Bulk polymerization was performed. While rapidly passing the reaction product discharged from the polymerization machine through a crusher, the reaction product was added to a 60 ° C. aqueous solution containing 0.05% by mass of triethylamine to deactivate the catalyst. Further, after separation, washing and drying, a crude polyacetal copolymer was obtained. Next, 4% by mass of a 4% by mass triethylamine aqueous solution was added to 100 parts by mass of the crude polyacetal resin, and the unstable part was removed by melting and kneading at 210 ° C. with a twin screw extruder. Further, 0.3 parts by mass of pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and 0.15 parts by mass of melamine were added as stabilizers. It was melt-kneaded at 210 ° C. with an extruder to obtain a pellet-shaped polyoxymethylene resin.

  In the case of the copolymer, when 1 kg of polyoxymethylene resin is incinerated, 1.47 kg of carbon dioxide is discharged. In the present invention, a polyoxymethylene resin is produced using a plant grown while absorbing carbon dioxide as a main raw material. Therefore, even if the polyoxymethylene resin is incinerated, an increase in the amount of carbon dioxide for 0.99 kg can be suppressed. it can.

<Example 2>
A polyoxymethylene resin was obtained in the same manner as in Example 1, except that 1,3-dioxolane, which is an auxiliary material used in Example 1, was derived from a plant material. Here, 1,3-dioxolane synthesized by a known method using plant-derived formaldehyde and plant-derived ethylene glycol as raw materials was used.

  In the case of the copolymer, when 1 kg of polyoxymethylene resin is incinerated, 1.47 kg of carbon dioxide is discharged. In the present invention, since the polyoxymethylene resin was produced using plants grown while absorbing carbon dioxide as all monomer raw materials, even if the polyoxymethylene resin was incinerated, an increase in the amount of carbon dioxide for 1.03 kg was suppressed. be able to.

Claims (5)

A first step of producing formaldehyde from methanol;
A second step of producing a polyoxymethylene resin from the formaldehyde obtained in the first step,
The said methanol is a manufacturing method of the polyoxymethylene resin containing the methanol which uses a plant as a raw material.   The said methanol is a manufacturing method of the polyoxymethylene resin of Claim 1 manufactured by using the glycerol obtained at the time of biodiesel manufacture as a raw material.   The method for producing a polyoxymethylene resin according to claim 1 or 2, wherein the second step is a step of producing trioxane from formaldehyde and producing a polyoxymethylene resin from the trioxane.   The method for producing a polyoxymethylene resin according to claim 3, wherein the polyoxymethylene resin is produced by copolymerizing the trioxane and a cyclic ether.   The method for producing a polyoxymethylene resin according to claim 4, wherein the cyclic ether is a cyclic ether derived from a plant.